Secondary comminution of wood pellets in power plant and laboratory-scale mills

- The influence of mill type on particle size and shape of milled wood was studied.
- Pellets were comminuted in power plant-scale roller and hammer mills.
- Comminution on power plant- and lab-scale roller mills was compared.
- A 2D dynamic imaging is used for particle characterization.
- The mill type has a significant influence on the particle size.

This study aims to determine the influence of mill type and pellet wood composition on particle size and shape of milled wood. The size and shape characteristics of pellets comminuted using power plant roller mills were compared with those obtained by using laboratory-scale roller- and hammer mills. A 2D dynamic imaging device was used for particle characterization. It was shown that mill type has a significant impact on particle size but an almost negligible effect on the shape of milled wood. Comminution in the pilot plant using a Loesche roller mill requires less energy than using a hammer mill, but generates a larger fraction of coarse particles. The laboratory-scale roller mill provides comparable results with the power plant roller mill with respect to particle size and shape.